Golf ball with temperature indicator

ABSTRACT

A golf ball having an integral means for sensing temperature whereby a golfer can readily determine if a golf ball is at the optimum temperature for play. For purposes of indicating temperature, the ball incorporates a thermochromic section that will change color or become transparent or translucent at a predetermined temperature. The thermochromic section may be printed in such a manner to indicate the condition of the ball.

FIELD OF THE INVENTION

[0001] The present invention relates to golf balls having integraltemperature sensors. The temperature sensor comprises a stamp or markthat changes color at a predetermined temperature, allowing a golfer todetermine the approximate temperature of a golf ball and hence itssuitability for play. Knowing the temperature of a golf ball is usefulin that it allows a golfer to determine when a golf ball is capable ofdelivering maximum performance when struck by a golf club.

BACKGROUND OF THE INVENTION

[0002] Generally, golf balls are one of three types. A first type is amulti-piece wound ball wherein a vulcanized rubber thread is wound undertension around a solid or semi-solid core, and thereafter enclosed in asingle or multi-layer covering of a tough, protective material. A secondtype of golf ball is a one-piece ball formed from a solid mass of aresilient material that has been cured to develop the necessary degreeof hardness to provide utility. One-piece molded balls do not have asecond enclosing cover. A third type of ball is a multi-piece non-woundball that includes a liquid, gel or solid core of one or more layers anda cover having one or more layers formed over the core.

[0003] Attempts to improve and/or optimize performance characteristicsin golf balls are typically directed toward achieving better feel whenthe ball is struck with a golf club, and also allowing for increased oroptimum distance while at the same time adhering to the rules set forthby the United States Golf Association (U.S.G.A.) regarding the physicalcharacteristics and performance properties of golf balls. These rulesspecify that the weight of a golf ball shall not be greater than 1.620ounces, the diameter of the ball shall not be less than 1.680 inches andthe velocity of the ball shall not be greater than 255 feet per second(250 feet per second with a 2% tolerance level). The U.S.G.A. rules alsospecify that the overall distance a golf ball should travel shall notcover an average distance (in carry and roll) greater then 280 yards,plus a 6% tolerance level (296.8 yards total).

[0004] Over the years, attempts to improve characteristics such as feeland durability have centered around the materials used to form thevarious layers of a golf ball. Improvements in spin and distancecharacteristics are usually directed toward the actual construction andphysical makeup of the golf ball. The use of one or more intermediatelayers between a core and a cover layer to achieve such improvements isknown in the art. The thickness and/or material hardness of each layermay also be varied in order to achieve a desired property.

[0005] In general, there is a natural transfer of energy that occurswithin a golf ball when the ball is struck by a golf club. Energy istransferred from the club face to the golf ball cover, and thensubsequently transferred through each layer beneath the cover. In solidnon-wound golf balls employing spherical layers, energy transfer isgenerally a function of the thickness and material composition of agiven layer. Therefore, varying either the thickness of a given layerand/or the material from which a layer is made affects the efficiency ofenergy transfer occurring within a golf ball and consequently affectsthe overall performance characteristics of that ball.

[0006] In both the wound and solid multi-layer golf balls, covers areplaced around the preformed cores by techniques such as injectionmolding, compression molding, casting etc. When the cover is placed onthe core, dimples are formed in the outer surface of the cover. Thisinvention is concerned with the cover of a golf ball.

[0007] There exists a need for a golf ball design that assists a golferin determining the approximate temperature of a golf ball and the ball'ssuitability for play in a given set of weather conditions. Knowing theball temperature allows a golfer to determine when the ball is capableof delivering maximum performance characteristics, such as spin andoverall distance.

[0008] Golf balls having surfaces that incorporate dyes that changecolor due to an environmental change are known in the prior art. In thisregard U.S. Pat. Nos. 5,938,544 and 5,823,891 to Winskowicz disclosegolf balls which incorporate microencapsulated dyes in the surfacethereof. These dyes change color upon prolonged exposure to water. Theinvention of these patents is useful for indicating when a golf ballbecomes a “water ball” as a result of a prolonged immersion in water.The dyes in question change color upon immersion and remain colored;they do not revert back to their original color.

[0009] Thermochromic materials have been incorporated into the face of agolf club for purposes of indicating the point of impact between a golfball and a golf club face. See, for example, U.S. Pat. No. 5,597,361 toHope, and U.S. Pat. No. 5,805,245 to Davis, which discloses the use ofthermochromic liquid crystals to indicate temperatures over differentranges. Similarly U.S. Pat. No. 5,394,824 to Johnson Jr. discloses theuse of thermochromic dyes to indicate the point of impact of a tennisball with a tennis court. Finally, the incorporation of thermochromicdyes into printing inks is disclosed in U.S. Pat. No. 4,717,710 toShimizu et al.

[0010] None of the patents discussed above discloses the use of a layerof a thermochromic material on the surface of a golf ball for purposesof indicating the temperature of said golf ball.

SUMMARY OF THE INVENTION

[0011] The present invention relates to new and improved golf balls thatovercome the above referenced problems. In this regard, the presentinvention is directed to golf balls having a temperature indicatingmechanism that indicates when a golf ball is at the optimum temperaturefor play.

[0012] In a first aspect, the present invention is directed to a golfball comprising a core and a cover. The cover on its surfaceincorporates a section comprising a thermochromic material. Thethermochromic material is capable of indicating whether the golf ball isabove or below a predetermined temperature. The thermochromic sectionmay be printed on the surface of the golf ball. The thermochromicmaterial is selected from the group consisting of cholesteric liquidcrystals and leuco dye systems.

[0013] In another aspect, the present invention is directed to a golfball comprising a core and a cover. The cover incorporates on itssurface an indicia that is covered with a thermochromic section. At apredetermined temperature, the thermochromic section becomes clear ortranslucent, thus allowing the observation of the indicia. The indiciamay be a color, a readable word, a logo, or any other suitableindication that the golf ball is suitable for play. The thermochromicmaterial is selected from the group consisting of cholesteric liquidcrystals and leuco dye systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following is a brief description of the drawings, which arepresented for the purpose of illustrating the invention and not for thepurposes of limiting the same.

[0015]FIG. 1 is a frontal view of a golf ball showing the application ofa temperature sensitive thermochromic compound onto a black stripe.

[0016]FIG. 2 is a frontal view of a golf ball showing the application ofa temperature sensitive thermochromic compound as a trademark.

[0017]FIG. 3 is a frontal view of a golf ball showing the application ofa temperature sensitive thermochromic compound as an indicia.

[0018]FIGS. 4A and 4B are frontal views of a golf ball before and afterthe temperature sensitive material becomes transparent or translucent.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] The major components of a golf ball are generally polymericmaterials. A golf ball functions as a result of its ability to transferthe kinetic energy of a moving golf club head to the golf ball. Theability to transfer this kinetic energy is related to the modulus ofelasticity of the various polymeric compounds that make up thecomponents of the golf ball. The modulus of elasticity of a polymervaries with temperature. Generally, the higher the temperature within agiven range, the higher the modulus of elasticity, and conversely, thelower the temperature, the lower the modulus of elasticity. Simplystated, as the temperature drops, golf balls become stiff and hencecannot be driven as far as when they are warm.

[0020] A golfer always strives for maximum performance from a golf ball.Maximum performance is often characterized by the length of a drive,with longer being better. In order to achieve maximum performance, agolf ball must be at an optimum temperature for playing. For practicalpurposes, this optimum temperature is generally from about 15 to about35° C., although individual golfers may prefer temperatures above orbelow this range.

[0021] Early or late in the golf season, particularly in certainclimates, golf balls can be well below these optimum temperatures. Thisis particularly true if golf balls have been left outside, for examplein the trunk of a car, or in an unheated location. It has been foundthat a golf ball stored outside or in an unheated area may have a balltemperature of O° C. or less, particularly early in the day.

[0022] Golfers have long recognized that cold golf balls do not performwell. As a way of warming golf balls golfers often place golf ballsinside their clothing so that body warmth might warm the golf balls.Some golfers use electric powered golf ball warmers to warm the golfballs. Regardless of which method is used, a golfer still has no way ofknowing when a golf ball is at an optimum temperature for play. Thisinvention is concerned with a golf ball that will indicate when a golfball is at optimum temperature for play.

[0023] In one preferred embodiment of the invention, there is a golfball comprising a core and a cover. The cover on its surfaceincorporates a section comprising a thermochromic material, wherein thethermochromic material is capable of indicating whether the golf ball isabove or below a predetermined temperature. In a preferred embodiment ofthe invention, the golf ball is stamped with an ink which incorporates athermochromic compound in such a manner that a positive indicia is givenas to whether a ball is in condition for play or not. Any type of golfball may be used, as long as the thermochromic material can beincorporated on or in the surface of the cover layer. In its simplestform, the stamp could indicate a word such as “PLAY” when the ball isabove a predetermined temperature that would constitute an optimumcondition, and “NO PLAY” when the golf ball is below said optimumtemperature, but any indicia may be used as long as the golfer knowswhich is suitable for play and which is not suitable for play. Forexample, “YES” and “NO” could also be used.

[0024] Referring to FIG. 1 it can be seen that golf ball 2 has aplurality of dimples 4. Golf ball 2 incorporates a printed band 6 thatis of a dark color. Printed on band 6 is a second band 8 thatincorporates the indicia PLAY. While band 8 can be printed in athermochromic compound it need not be and can be printed in normal ink.Printed on band 6 is a third band 10, which is printed with an ink thatincorporates a thermochromic compound. When the temperature of ball 2drops to a predetermined level the “NO” indicia becomes visible. This“NO” indicia indicates that the golf ball is at such a temperature thatis not optimum, and it would be best not to play the golf ball.

[0025] In another embodiment, band 10 can be eliminated and band 8 wouldnot incorporate the indicia “PLAY”. Instead, band 8 would be printedwith a thermochromic compound which incorporates an ink which changescolor at a predetermined temperature. For example, if band 8 was onecolor, such as green, the golfer would know that the golf ball was incondition for play. Conversely, if band 8 was another color, such asred, the golfer would know that ball was not be in condition for play.

[0026]FIG. 2 illustrates still another embodiment of this inventionwherein golf ball 2 with dimples 4 has a trademark 12 imprinted thereon.Trademark 12 is imprinted with an ink that incorporates a thermochromiccompound that changes color at a given temperature. In this instance, iftrademark 12 is one color, such as green, the golf ball is suitable forplay. In contrast, if trademark 12 is another color such as red, thiswould indicate that ball is not in condition for play.

[0027] In another preferred embodiment, the invention comprises a golfball comprising a core and a cover. The cover incorporates on itssurface an indicia, wherein the indicia is covered with a thermochromicsection, and wherein the thermochromic section becomes clear ortranslucent at a predetermined temperature, thereby allowing theobservation of the indicia. As shown in FIG. 3, indicia 14 is printedwithout a contrasting stripe. When the ball is in condition for play,indicia 14 would indicate this by, for example, displaying the word“PLAY”. If the ball is not at an optimum temperature and therefore notsuitable for play, the band would not show the indicia at all.

[0028] Another golf ball according to this preferred embodiment isillustrated in FIGS. 4A and 4B. A golf ball 2 having dimples 4incorporates an indicia 16. When the temperature is too cold for play,the indicia 16 is opaque, as shown in FIG. 4A. When the temperature ofgolf ball is warm enough for play, the indicia 16 becomes transparent ortranslucent such that the indicia becomes visible, as shown in FIG. 4B.

[0029] Relative to the description of FIGS. 1, 3 and 4 above, theindicia “PLAY” and “NO PLAY” are discussed as examples for illustrativepurposes only, but it is understood by one skilled in the art that otherwording, symbols or marks could be utilized.

[0030] The golf ball of the invention preferably comprises a cover layerdisposed about the core. The cover may be a single cover layer oroptionally a multi-layer cover. The cover layer is constructed from anysuitable cover material known in the golf ball art. Furthermore, themantle layers may contain a plurality of protuberances. Suitable covermaterials are more fully described herein.

[0031] Additionally, it is contemplated that golf balls employing a coreaccording to the present invention may have one or more mantle layersdisposed between the core and the cover layer or layers. Suitable mantlelayer materials are more fully described herein.

[0032] Preferred cover materials are natural and synthetic balata,various ionomers and non-ionomers, such as polyurethanes, and blendsthereof. lonomer covers and some non-ionomer covers are very durable andresult in what is referred to as “cut proof” golf balls.

[0033] The cover and mantle layers of golf balls according to thepresent invention may comprise any material suitable for use as a golfball mantle. Examples of preferred materials include, but are notlimited to, ionomer resins, non-ionomer resins such as nyloncompositions, thermoplastics compositions, thermoset compositions, andpolyurethane materials.

[0034] With respect to a preferred ionomeric cover or mantle layercomposition of the invention, ionomeric resins are polymers containinginterchain ionic bonding. As a result of their toughness, durability,and flight characteristics, various ionomeric resins sold by E.I. DuPontde Nemours & Company under the trademark SURLYN®, and by the ExxonCorporation (see U.S. Pat. No. 4,911,451, incorporated herein byreference) under the trademarks ESCOR® and IOTEK®, have become thematerials of choice for the construction of golf ball layers over thetraditional “balata” (transpolyisoprene, natural or synthetic) rubbers.

[0035] The cover layer(s) can also be formed from a number of othernon-ionomeric thermoplastics and thermosets. For example, lower costpolyolefins and thermoplastic elastomers can be used. Non-limitingexamples of suitable non-ionomeric polyolefin materials include lowdensity polyethylene, linear low density polyethylene, high densitypolyethylene, polypropylene, rubber-toughened olefin polymers, acidcopolymers which do not become part of an ionomeric copolymer when usedin the inner cover layer, such as PRIMACOR®, NUCREL®, ESCOR® and ATX,plastomers and flexomers, thermoplastic elastomers such asstyrene/butadiene/styrene (SBS) or styrene/ethylene-butylene/styrene(SEBS) block copolymers, including KRATON® (Shell), dynamicallyvulcanized elastomers such as SANTOPRENE® (Monsanto), ethylene vinylacetates such as ELVAX® (DuPont), ethylene methyl acrylates such asOPTEMA® (Exxon), polyvinyl chloride resins, and other elastomericmaterials may be used. Mixtures, blends, or alloys involving thematerials described above can be used. The cover layer(s) optionally mayinclude processing aids, release agents and/or diluents.

[0036] Cores according to the present invention may be formed from anysuitable core material known in the golf ball art. The core may beformed from a natural or synthetic rubber such as polybutadiene orpolyisoprene, a thermoset material, a thermoplastic material, orcombinations thereof.

[0037] The cores generally have a weight of about 25 to 40 grams andpreferably about 30 to 40 grams and can be molded from a variety ofmaterials. As an example, the core can be molded from a slug of uncuredor lightly cured elastomer composition comprising a high cis contentpolybutadiene and a metal salt of an ethylenically unsaturatedcarboxylic acid such as zinc mono-or diacrylate or methacrylate. Toachieve higher coefficients of restitution and/or to increase hardnessin the core, the amount of zinc diacrylate co-agent may be increased. Inaddition, larger amounts of metal oxide such as zinc oxide may beincluded in order to increase the core weight so that the finished ballmore closely approaches the U.S.G.A. upper weight limit of 1.620 ounces.Non-limiting examples of other materials which may be used in the corecomposition include compatible rubbers or ionomers, and low molecularweight fatty acids such as stearic acid. Free radical initiatorcatalysts such as peroxides are mixed with the core composition so thaton the application of heat and pressure, a curing or cross-linkingreaction takes place.

[0038] Materials suitable for a mantle layer include any of thosepreviously listed as materials suitable for a cover layer, as well asthose suitable for a core or core layer.

[0039] Energy transfer within a golf ball is a function of the thicknessof the respective layers, the size, shape and the materials used to formthe respective layers. Physical properties of a golf ball of the presentinvention may be adjusted and optimized by varying the compositions andthickness of individual layers and also by variations in the surfacetopography of one or more mantle layers. A golf ball functions by theflexing of the respective core and cover layers when the golf ball isstruck with a golf club. As a result of the flexing, kinetic energy istransferred from a moving golf club head to the golf ball, causing thegolf ball to be propelled a great distance.

[0040] The ability of a golf ball to transfer energy from a moving golfclub head to itself is controlled by the modulus of elasticity of thematerials, which are generally polymers, that make up the variouscomponents of a golf ball. The modulus of elasticity of a polymer varieswith temperature. Generally, the higher the temperature within a givenrange, the higher the modulus of elasticity. In view of this, it istherefore desirable that a golf ball be played under optimum temperatureconditions. This invention provides a qualitative indication of the golfball temperature, thereby allowing a golfer to determine when a golfball is at the optimum temperature for play. The golf balls of thepresent invention incorporate in or on the surface of the golf ball athermochromic compounds, such as cholesteric liquid crystals, a leucodye system or a combination thereof.

[0041] The thermochromic compound may be placed over another printedarea, such as, for example, a black stripe or printed words. As thetemperature of the golf ball changes, the thermochromic compound changescolor or becomes translucent or transparent. This change in color isuseful to indicate when the golf ball is at the optimum temperature forplay.

[0042] The thermochromic compound may be printed in such a manner as topresent a readable indication of the condition of the golf ball. Forexample, various different thermochromic compounds can be chosen andprinted to indicate a “NO PLAY” condition at one temperature and a“PLAY” condition at another temperature.

[0043] In the manufacture of golf balls, the last step in themanufacturing process is generally a painting or finishing step. In someinstances, a semi finished ball is printed and clear coated. In manycases, the semi finished golf ball is primed, painted if necessary,printed and clear coated. Many covers do not need to be painted ifpigments and optical brighteners are utilized. See, for example, U.S.Pat. No. 4,679,795 to Melvin et al., incorporated by reference herein.In one embodiment of this invention, the application of thethermochromic compound is after the above described priming or printingstep. The printing is then covered and protected with a clear coat. Thethermochromic material may be put on in different steps as well, asdescribed below.

[0044] In accordance with another embodiment of the invention, thethermochromic indicia may be applied over the clear coat. In thisembodiment, the thermochromic indicia may be composed of a durable inksuch as a two part polyurethane system or an ultraviolet cured oligomertype ink, or any other ink or printing system known in the art.

[0045] In still another embodiment, the thermochromic indicia may beapplied directly to the cover of the golf ball, provided that steps aretaken to make sure that proper adhesion occurs between the thermochromicindicia and the golf ball surfaces. The cover may then be clear coated,if desired.

[0046] Thermochromic compounds may be reversible or irreversible. Asused herein, the term irreversible thermochromic compound means that thethermochromic compound remains in its altered state after its initialstimulus. As used herein, the term reversible thermochromic compoundmeans that the thermochromic compound returns to its initial state aftera return to the initial temperature. For use in this invention,reversible thermochromic compounds are preferred, thereby allowingtemperature indication, and hence the suitability for play of the golfball over its entire life.

[0047] A preferred thermochromic compounds for use in this invention arecholesteric liquid crystals. Preferred liquid crystals are cholestericliquid crystals that have nuclear structures that can be made to expandor contract with temperature changes. These cholesteric liquid crystalscan be readily compounded with printing ink vehicles to form suitableprinting inks for application to golf ball surfaces.

[0048] Another preferred thermochromic compound for use in the presentinvention is a leuco dye system. Leuco dye systems measure temperaturechange less precisely than the cholesteric liquid crystals. When a leucodye system is utilized as a thermochromic compound, the temperatureresponse of the indicia on the golf ball is less precise. However, theleuco dye system is much more solvent resistant and less ultravioletsensitive, and therefore it may be preferred for use on golf balls.

[0049] Thermochromic leuco dye systems are also referred to as “whitedyes”. They are named such due to the colorless state that they are inunder certain conditions (i.e. pH, temperature, UV radiation). Theseleuco dye systems are typically used in a microencapsulated multicomponent mixture. Generally, the first component of the leuco dyesystem is a spirolactone such as fluorans or crystal violet lactone,spiropyrans or fulgides.

[0050] The second component is generally a color developer. The colordeveloper is often referred to as an “electron acceptor”, but it is moreaccurately described as a proton donor that can affect the equilibriumof the dye system. The color developer is typically a weak acid.Examples that may be suitable for use in the present invention include,but are not limited to, bisphenol A, 1,2,3 triazoles (such as1,2,3-benzotriazole and 1,2,3-triazole ethyl 4-methyl-5-carboxylate),octyl phydroxybenzoate and 4-hydroxycoumarin derivatives.

[0051] The third component of the leuco dye system is generally a polarsolvent. Examples of polar solvents include, but are not limited to,lauryl alcohol, cetyl alcohol and butyl stearate. The polar solvent isan important component since it is the melting point of this componentthat controls the temperature at which the color change will take place.

[0052] These microencapsulated materials are typically colored at lowtemperatures (below the melting point of the solvent) and colorless athigher temperatures.

[0053] An example of a leuco dye system is one that generally containsthe following components:

[0054] 1. leuco dye (such as crystal violet lactone);

[0055] 2. weak acid (such as 1,2,3-benzotriazole);

[0056] 3. solvent (such as lauryl alcohol); and optionally

[0057] 4. salt (such as myristylammonium oleate).

[0058] The salt dissociates at high temperature into amine andcarboxylic acids, and this dissociation raises the pH of the system andcauses the dye to take up its colorless closed-ring form.

[0059] In the microencapsulated state, these leuco dye systems are thepreferred embodiment for use in this invention.

EXAMPLES

[0060] The present invention will be described in greater detail withreference to the following Examples. All formulations listed in theExamples are parts by weight unless otherwise specified.

Example 1

[0061] A golf ball having an ionomer cover was primed by sprayingapproximately a 1 mil coating of a primer having the followingcomposition in parts by weight. Polyurethane dispersion 100.0Polyaziridine-crosslinker 5.0 Water 5.0 Total: 110.0

[0062] The primer coating was then dried for 20 minutes at temperatureof about 50° C. A black band was then applied around the ball. The blackband consisted of a carbon pigment in an ultraviolet cured ink. Thisblack band was then cured for 2 minutes using ultraviolet radiation.

[0063] A thermochromic logo of the cholesteric liquid crystal type wasthen printed over a portion of the black band. The color at optimumtemperature was green. The liquid crystal printing ink is commerciallyavailable from the Hallcrest Limited Company (Glenview, III.) as C-17-10TLC.

[0064] The golf ball was then air dried at a temperature of 120° F. for20 minutes. The resulting golf ball was then cooled to a temperature of10° C. The thermochromic logo was black. The golf ball was then slowlyreheated at a temperature of 25° C. where upon the logo changed to agreen color. The printed green thermochromic logo strongly contrastedagainst the black stripe.

Example 2

[0065] A golf ball primed with a waterborne primer was printed with theword “MAN” using a UV cured black ink. A thermochromic ink containing aleuco dye system was printed over the “MAN” indicia. The formula of thethermochromic ink was: Leuco dye Powder (Green 31 Ct) 100 gramsPolyurethane dispersion 20.0 grams Defoamer 4 drops Deionized water 2.0grams

[0066] The leuco dye powders are commercially available from ColorChange Corporation, Addison, Ill..

[0067] Although the formulation is proprietary, Applicant believes thatthe leuco dye powder was a microencapsulated, multi component materialcontaining at least a dye, a color developer and a solvent. Applicantspeculates that the leuco dye powder may also contain a salt thatdissociates at high temperature, changing the pH of the system.

[0068] This overprint, thermochromic ink was dried for 20 minutes at120° F. The resultant ink was green and opaque when dried at 25° C. Whenthe ball was heated to 35° C., the green thermochromic ink becametransparent and the “MAN” indicia became visible.

[0069] The foregoing description is considered to describe the preferredembodiments of the present invention. However, it is contemplated thatvarious changes and modifications apparent to those skilled in the artmay be made without departing from the present invention. Therefore, theforegoing description is intended to cover all such changes andmodifications encompassed within the spirit and scope of the presentinvention, including all equivalents.

What is claimed is:
 1. A golf ball comprising a core and a cover whereinsaid cover on its surface incorporates a section comprising athermochromic material, wherein the thermochromic material is capable ofindicating whether the golf ball is above or below a predeterminedtemperature.
 2. The golf ball of claim 1 wherein the thermochromicsection is printed onto the surface of the golf ball.
 3. The golf ballof claim 1 wherein the temperature indication is a visible indication.4. The golf ball of claim 3 wherein the visible indication is in twoparts, wherein the first part is permanently displayed, and the secondpart is displayed after activation by a temperature change.
 5. The golfball of claim 1 wherein a first section comprising an ink material isfirst created on the surface of said golf ball, the thermochromicsection is applied over the first section, and wherein the color of theink material is different from the color of the thermochromic section.6. The golf of claim 1 wherein the thermochromic material is a memberselected from the group consisting of cholesteric liquid crystals andleuco dye systems.
 7. The golf ball of claim 1 wherein the thermochromicmaterial comprises cholesteric liquid crystals.
 8. The golf ball ofclaim 1, wherein the thermochromic material comprises a leuco dyesystem.
 9. The golf ball of claim 1, wherein the cover comprises atleast one inner cover layer and at least one outer cover layer.
 10. Agolf ball comprising a core and a cover wherein said cover incorporateson its surface an indicia, wherein the indicia is covered with athermochromic section, and wherein the thermochromic section becomesclear or translucent at a predetermined temperature, thereby allowingthe observation of the indicia.
 11. The golf ball of claim 10 whereinthe indicia is a color.
 12. The golf ball of claim 10 wherein theindicia is a readable word or logo.
 13. The golf ball of claim 10wherein the thermochromic material is a member selected from the groupconsisting of cholesteric liquid crystals and leuco dye systems.
 14. Thegolf ball of claim 13 wherein the thermochromic material comprises aleuco dye system.
 15. A golf ball comprising a core and a cover whereinsaid cover incorporates a thermochromic section on its surface toindicate whether said golf ball is above or below a predeterminedtemperature, said thermochromic section comprising a thermochromicmaterial selected from the group consisting of cholesteric liquidcrystals and leuco dye systems.
 16. The golf ball of claim 15 whereinsaid thermochromic section is a visible indication printed on thesurface of the golf ball.
 17. The golf ball of claim 15 wherein saidthermochromic section becomes clear or translucent at a predeterminedtemperature, thereby displaying an indicia printed on the surface of theball under the thermochromic section.
 18. The golf ball of claim 15,wherein the thermochromic material comprises cholesteric liquidcrystals.
 19. The golf ball of claim 17 wherein the indicia is areadable word or logo.
 20. The golf ball of claim 15 wherein the covercomprises at least one inner cover layer and at least one outer coverlayer.